Calciferous and similar deposits occur in body fluid passages of various types. Of particular interest are kidney and gall stones as well as arterial plaque.
Radiation in various forms has been used for destroying or removing such deposits from the internal passages of the body. In one form of laser therapy, radiation is directed onto a light-receiving surface of a heat-generating element. The element is then placed in contact with the target deposit, melting it. This approach has several drawbacks which include:
1. thermal damage to surrounding tissue;
2. only fatty plaques readily melt;
3. more advanced fibrous and calcified plaques form char and debris; and
4. the hot element adheres to the tissue rupturing it when the element is removed.
In another approach, laser radiation is applied directly to the target deposit to ablate it or produce shock waves that induce fragmentation. Direct lasertripsy has several disadvantages. Laser energy often damages healthy tissue surrounding the target deposit by direct absorption or by acting as a general heat sink for the high temperature plasma. Some deposits only weakly absorb radiation thereby requiring greater radiation exposure and damage. A sharp laser delivery fiber can cause damage if inadvertently jabbed into healthy tissue.